New onset of venous thromboembolism among hospitalized patients at Brigham and Women's Hospital is caused more often by prophylaxis failure than by withholding treatment.

CONTEXT: Guidelines to prevent venous thromboembolism (VTE) have been widely distributed and generally have been assumed to be effective. Therefore, among hospitalized patients, the development of VTE is thought to occur in the context of omitted prophylaxis.
OBJECTIVES: To describe hospitalized patients who develop VTE and to determine whether they received antecedent prophylaxis.
DESIGN: Case series.
SETTING: Brigham and Women's Hospital. PATIENTS: Three hundred eighty-four patients who developed in-hospital deep venous thrombosis or pulmonary embolism or who developed VTE within 30 days of prior hospital discharge. MAIN OUTCOME MEASURES: The relationship of developing new-onset VTE to the use or omission of antecedent in-hospital prophylaxis.
RESULTS: Of the 384 identified patients, 272 had deep venous thrombosis alone, 62 had pulmonary embolism alone, and 50 had deep venous thrombosis and pulmonary embolism. Most were medical service patients; fewer than one fourth were general or orthopedic surgery patients. Overall, 52% had received antecedent VTE prophylaxis. Thirteen deaths (3.4%) were ascribed to pulmonary embolism, and prophylaxis was omitted in only 1 of those 13 patients.
CONCLUSIONS: Most deaths from pulmonary embolism among patients hospitalized for other conditions occurred in the setting of failed prophylaxis rather than omitted prophylaxis. High-risk patients, especially medical service patients, warrant intensive VTE prophylaxis and close follow-up to ensure successful outcomes.